fs/sdcardfs/packagelist.c

   1 /*
   2  * fs/sdcardfs/packagelist.c
   3  *
   4  * Copyright (c) 2013 Samsung Electronics Co. Ltd
   5  *   Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
   6  *               Sunghwan Yun, Sungjong Seo
   7  *
   8  * This program has been developed as a stackable file system based on
   9  * the WrapFS which written by
  10  *
  11  * Copyright (c) 1998-2011 Erez Zadok
  12  * Copyright (c) 2009     Shrikar Archak
  13  * Copyright (c) 2003-2011 Stony Brook University
  14  * Copyright (c) 2003-2011 The Research Foundation of SUNY
  15  *
  16  * This file is dual licensed.  It may be redistributed and/or modified
  17  * under the terms of the Apache 2.0 License OR version 2 of the GNU
  18  * General Public License.
  19  */
  20
  21 #include "sdcardfs.h"
  22 #include <linux/hashtable.h>
  23 #include <linux/delay.h>
  24
  25
  26 #include <linux/init.h>
  27 #include <linux/module.h>
  28 #include <linux/slab.h>
  29
  30 #include <linux/configfs.h>
  31
  32 struct hashtable_entry {
  33         struct hlist_node hlist;
  34         const char *key;
  35         atomic_t value;
  36 };
  37
  38 static DEFINE_HASHTABLE(package_to_appid, 8);
  39
  40 static struct kmem_cache *hashtable_entry_cachep;
  41
  42 static unsigned int str_hash(const char *key) {
  43         int i;
  44         unsigned int h = strlen(key);
  45         char *data = (char *)key;
  46
  47         for (i = 0; i < strlen(key); i++) {
  48                 h = h * 31 + *data;
  49                 data++;
  50         }
  51         return h;
  52 }
  53
  54 appid_t get_appid(const char *app_name)
  55 {
  56         struct hashtable_entry *hash_cur;
  57         unsigned int hash = str_hash(app_name);
  58         appid_t ret_id;
  59
  60         rcu_read_lock();
  61         hash_for_each_possible_rcu(package_to_appid, hash_cur, hlist, hash) {
  62                 if (!strcasecmp(app_name, hash_cur->key)) {
  63                         ret_id = atomic_read(&hash_cur->value);
  64                         rcu_read_unlock();
  65                         return ret_id;
  66                 }
  67         }
  68         rcu_read_unlock();
  69         return 0;
  70 }
  71
  72 /* Kernel has already enforced everything we returned through
  73  * derive_permissions_locked(), so this is used to lock down access
  74  * even further, such as enforcing that apps hold sdcard_rw. */
  75 int check_caller_access_to_name(struct inode *parent_node, const char* name) {
  76
  77         /* Always block security-sensitive files at root */
  78         if (parent_node && SDCARDFS_I(parent_node)->perm == PERM_ROOT) {
  79                 if (!strcasecmp(name, "autorun.inf")
  80                         || !strcasecmp(name, ".android_secure")
  81                         || !strcasecmp(name, "android_secure")) {
  82                         return 0;
  83                 }
  84         }
  85
  86         /* Root always has access; access for any other UIDs should always
  87          * be controlled through packages.list. */
  88         if (from_kuid(&init_user_ns, current_fsuid()) == 0) {
  89                 return 1;
  90         }
  91
  92         /* No extra permissions to enforce */
  93         return 1;
  94 }
  95
  96 /* This function is used when file opening. The open flags must be
  97  * checked before calling check_caller_access_to_name() */
  98 int open_flags_to_access_mode(int open_flags) {
  99         if((open_flags & O_ACCMODE) == O_RDONLY) {
 100                 return 0; /* R_OK */
 101         } else if ((open_flags & O_ACCMODE) == O_WRONLY) {
 102                 return 1; /* W_OK */
 103         } else {
 104                 /* Probably O_RDRW, but treat as default to be safe */
 105                 return 1; /* R_OK | W_OK */
 106         }
 107 }
 108
 109 static struct hashtable_entry *alloc_packagelist_entry(const char *key,
 110                 appid_t value)
 111 {
 112         struct hashtable_entry *ret = kmem_cache_alloc(hashtable_entry_cachep,
 113                         GFP_KERNEL);
 114         if (!ret)
 115                 return NULL;
 116
 117         ret->key = kstrdup(key, GFP_KERNEL);
 118         if (!ret->key) {
 119                 kmem_cache_free(hashtable_entry_cachep, ret);
 120                 return NULL;
 121         }
 122
 123         atomic_set(&ret->value, value);
 124         return ret;
 125 }
 126
 127 static int insert_packagelist_entry_locked(const char *key, appid_t value)
 128 {
 129         struct hashtable_entry *hash_cur;
 130         struct hashtable_entry *new_entry;
 131         unsigned int hash = str_hash(key);
 132
 133         hash_for_each_possible_rcu(package_to_appid, hash_cur, hlist, hash) {
 134                 if (!strcasecmp(key, hash_cur->key)) {
 135                         atomic_set(&hash_cur->value, value);
 136                         return 0;
 137                 }
 138         }
 139         new_entry = alloc_packagelist_entry(key, value);
 140         if (!new_entry)
 141                 return -ENOMEM;
 142         hash_add_rcu(package_to_appid, &new_entry->hlist, hash);
 143         return 0;
 144 }
 145
 146 static void fixup_perms(struct super_block *sb, const char *key) {
 147         if (sb && sb->s_magic == SDCARDFS_SUPER_MAGIC) {
 148                 fixup_perms_recursive(sb->s_root, key, strlen(key));
 149         }
 150 }
 151
 152 static void fixup_all_perms(const char *key)
 153 {
 154         struct sdcardfs_sb_info *sbinfo;
 155         list_for_each_entry(sbinfo, &sdcardfs_super_list, list)
 156                 if (sbinfo)
 157                         fixup_perms(sbinfo->sb, key);
 158 }
 159
 160 static int insert_packagelist_entry(const char *key, appid_t value)
 161 {
 162         int err;
 163
 164         mutex_lock(&sdcardfs_super_list_lock);
 165         err = insert_packagelist_entry_locked(key, value);
 166         if (!err)
 167                 fixup_all_perms(key);
 168         mutex_unlock(&sdcardfs_super_list_lock);
 169
 170         return err;
 171 }
 172
 173 static void free_packagelist_entry(struct hashtable_entry *entry)
 174 {
 175         kfree(entry->key);
 176         hash_del_rcu(&entry->hlist);
 177         kmem_cache_free(hashtable_entry_cachep, entry);
 178 }
 179
 180 static void remove_packagelist_entry_locked(const char *key)
 181 {
 182         struct hashtable_entry *hash_cur;
 183         unsigned int hash = str_hash(key);
 184
 185         hash_for_each_possible_rcu(package_to_appid, hash_cur, hlist, hash) {
 186                 if (!strcasecmp(key, hash_cur->key)) {
 187                         hash_del_rcu(&hash_cur->hlist);
 188                         synchronize_rcu();
 189                         free_packagelist_entry(hash_cur);
 190                         return;
 191                 }
 192         }
 193 }
 194
 195 static void remove_packagelist_entry(const char *key)
 196 {
 197         mutex_lock(&sdcardfs_super_list_lock);
 198         remove_packagelist_entry_locked(key);
 199         fixup_all_perms(key);
 200         mutex_unlock(&sdcardfs_super_list_lock);
 201         return;
 202 }
 203
 204 static void packagelist_destroy(void)
 205 {
 206         struct hashtable_entry *hash_cur;
 207         struct hlist_node *h_t;
 208         HLIST_HEAD(free_list);
 209         int i;
 210         mutex_lock(&sdcardfs_super_list_lock);
 211         hash_for_each_rcu(package_to_appid, i, hash_cur, hlist) {
 212                 hash_del_rcu(&hash_cur->hlist);
 213                 hlist_add_head(&hash_cur->hlist, &free_list);
 214
 215         }
 216         synchronize_rcu();
 217         hlist_for_each_entry_safe(hash_cur, h_t, &free_list, hlist)
 218                 free_packagelist_entry(hash_cur);
 219         mutex_unlock(&sdcardfs_super_list_lock);
 220         printk(KERN_INFO "sdcardfs: destroyed packagelist pkgld\n");
 221 }
 222
 223 struct package_details {
 224         struct config_item item;
 225         const char *name;
 226 };
 227
 228 static inline struct package_details *to_package_details(struct config_item *item)
 229 {
 230         return item ? container_of(item, struct package_details, item) : NULL;
 231 }
 232
 233 static ssize_t package_details_appid_show(struct config_item *item, char *page)
 234 {
 235         return scnprintf(page, PAGE_SIZE, "%u\n", get_appid(to_package_details(item)->name));
 236 }
 237
 238 static ssize_t package_details_appid_store(struct config_item *item,
 239                                        const char *page, size_t count)
 240 {
 241         unsigned int tmp;
 242         int ret;
 243
 244         ret = kstrtouint(page, 10, &tmp);
 245         if (ret)
 246                 return ret;
 247
 248         ret = insert_packagelist_entry(to_package_details(item)->name, tmp);
 249
 250         if (ret)
 251                 return ret;
 252
 253         return count;
 254 }
 255
 256 static void package_details_release(struct config_item *item)
 257 {
 258         struct package_details *package_details = to_package_details(item);
 259         printk(KERN_INFO "sdcardfs: removing %s\n", package_details->name);
 260         remove_packagelist_entry(package_details->name);
 261         kfree(package_details->name);
 262         kfree(package_details);
 263 }
 264
 265 CONFIGFS_ATTR(package_details_, appid);
 266
 267 static struct configfs_attribute *package_details_attrs[] = {
 268         &package_details_attr_appid,
 269         NULL,
 270 };
 271
 272 static struct configfs_item_operations package_details_item_ops = {
 273       .release = package_details_release,
 274 };
 275
 276 static struct config_item_type package_appid_type = {
 277         .ct_item_ops    = &package_details_item_ops,
 278         .ct_attrs       = package_details_attrs,
 279         .ct_owner       = THIS_MODULE,
 280 };
 281
 282 static struct config_item *packages_make_item(struct config_group *group, const char *name)
 283 {
 284         struct package_details *package_details;
 285
 286         package_details = kzalloc(sizeof(struct package_details), GFP_KERNEL);
 287         if (!package_details)
 288                 return ERR_PTR(-ENOMEM);
 289         package_details->name = kstrdup(name, GFP_KERNEL);
 290         if (!package_details->name) {
 291                 kfree(package_details);
 292                 return ERR_PTR(-ENOMEM);
 293         }
 294
 295         config_item_init_type_name(&package_details->item, name,
 296                                    &package_appid_type);
 297
 298         return &package_details->item;
 299 }
 300
 301 static ssize_t packages_list_show(struct config_item *item, char *page)
 302 {
 303         struct hashtable_entry *hash_cur;
 304         int i;
 305         int count = 0, written = 0;
 306         const char errormsg[] = "<truncated>\n";
 307
 308         rcu_read_lock();
 309         hash_for_each_rcu(package_to_appid, i, hash_cur, hlist) {
 310                 written = scnprintf(page + count, PAGE_SIZE - sizeof(errormsg) - count, "%s %d\n",
 311                                         (const char *)hash_cur->key, atomic_read(&hash_cur->value));
 312                 if (count + written == PAGE_SIZE - sizeof(errormsg)) {
 313                         count += scnprintf(page + count, PAGE_SIZE - count, errormsg);
 314                         break;
 315                 }
 316                 count += written;
 317         }
 318         rcu_read_unlock();
 319
 320         return count;
 321 }
 322
 323 static struct configfs_attribute packages_attr_packages_gid_list = {
 324         .ca_name        = "packages_gid.list",
 325         .ca_mode        = S_IRUGO,
 326         .ca_owner       = THIS_MODULE,
 327         .show           = packages_list_show,
 328 };
 329
 330 static struct configfs_attribute *packages_attrs[] = {
 331         &packages_attr_packages_gid_list,
 332         NULL,
 333 };
 334
 335 /*
 336  * Note that, since no extra work is required on ->drop_item(),
 337  * no ->drop_item() is provided.
 338  */
 339 static struct configfs_group_operations packages_group_ops = {
 340         .make_item      = packages_make_item,
 341 };
 342
 343 static struct config_item_type packages_type = {
 344         .ct_group_ops   = &packages_group_ops,
 345         .ct_attrs       = packages_attrs,
 346         .ct_owner       = THIS_MODULE,
 347 };
 348
 349 static struct configfs_subsystem sdcardfs_packages = {
 350         .su_group = {
 351                 .cg_item = {
 352                         .ci_namebuf = "sdcardfs",
 353                         .ci_type = &packages_type,
 354                 },
 355         },
 356 };
 357
 358 static int configfs_sdcardfs_init(void)
 359 {
 360         int ret;
 361         struct configfs_subsystem *subsys = &sdcardfs_packages;
 362
 363         config_group_init(&subsys->su_group);
 364         mutex_init(&subsys->su_mutex);
 365         ret = configfs_register_subsystem(subsys);
 366         if (ret) {
 367                 printk(KERN_ERR "Error %d while registering subsystem %s\n",
 368                        ret,
 369                        subsys->su_group.cg_item.ci_namebuf);
 370         }
 371         return ret;
 372 }
 373
 374 static void configfs_sdcardfs_exit(void)
 375 {
 376         configfs_unregister_subsystem(&sdcardfs_packages);
 377 }
 378
 379 int packagelist_init(void)
 380 {
 381         hashtable_entry_cachep =
 382                 kmem_cache_create("packagelist_hashtable_entry",
 383                                         sizeof(struct hashtable_entry), 0, 0, NULL);
 384         if (!hashtable_entry_cachep) {
 385                 printk(KERN_ERR "sdcardfs: failed creating pkgl_hashtable entry slab cache\n");
 386                 return -ENOMEM;
 387         }
 388
 389         configfs_sdcardfs_init();
 390         return 0;
 391 }
 392
 393 void packagelist_exit(void)
 394 {
 395         configfs_sdcardfs_exit();
 396         packagelist_destroy();
 397         if (hashtable_entry_cachep)
 398                 kmem_cache_destroy(hashtable_entry_cachep);
 399 }